1. Field of the Invention
The invention relates to an electrostatic chucking technology used in a semiconductor device manufacturing process or a liquid crystal panel manufacturing process.
2. Description of the Related Art
In the semiconductor device manufacturing process, an electrostatic chucking method is used as a method of chucking a semiconductor wafer on a stage of an etching apparatus and so on in each of processes such as etching, CVD (chemical vapor deposition), PVD (physical vapor deposition), and so on. This electrostatic chucking method is to apply a voltage between a stage and a semiconductor wafer set on this stage with a dielectric layer therebetween to chuck the semiconductor wafer on the stage with static electricity generated therebetween.
In this electrostatic chucking method, however, on principle, since it is necessary to use the stage as one electrode and a workpiece (e.g. a semiconductor wafer) as another electrode, an insulator can not be chucked on the stage as the workpiece. For example, since an insulation substrate is used in a device of SOS (silicon-on-sapphire) or SOI (silicon-on-insulator), high chucking force such as obtained by the semiconductor wafer can not be obtained and thus the electrostatic chucking method can not be used for such a device. Furthermore, since a FPD (flat-panel display) or a DVD (digital video disk) uses an insulation substrate such as a glass substrate, too, the electrostatic chucking technology can not be used for these.
The relevant technology is disclosed in the Japanese Patent Application Publications Nos. Hei. 5-63062, Hei. 5-331431, and Sho. 62-275137.
As described above, in an electrostatic chucking type apparatus, a workpiece formed of an insulator can not be chucked on a stage. Therefore, it is necessary to chuck such a workpiece by a mechanical clamp mechanism in an apparatus that performs processes in a vacuum state, such as a etching apparatus, a CVD apparatus, or a PVD apparatus. However, such a clamp mechanism causes instability of the temperature distribution in the workpiece and reduction of processing accuracy by the workpiece warping, thereby reducing the yield. For solving this, an electrostatic chucking technology capable of chucking a workpiece formed of an insulator or a workpiece attached with an object to be processed such as a semiconductor wafer on the stage has been required.